Xampp mysql Error: MySQL shutdown unexpectedly

when I starting mysql, giving the following error:

17:43:13  [mysql]   Error: MySQL shutdown unexpectedly.
17:43:13  [mysql]   This may be due to a blocked port, missing dependencies, 
17:43:13  [mysql]   improper privileges, a crash, or a shutdown by another method.
17:43:13  [mysql]   Press the Logs button to view error logs and check
17:43:13  [mysql]   the Windows Event Viewer for more clues
17:43:13  [mysql]   If you need more help, copy and post this
17:43:13  [mysql]   entire log window on the forums

then, I check the mysql_error.log:

    2017-05-03 17:39:39 202c InnoDB: Warning: Using innodb_additional_mem_pool_size is DEPRECATED. This option may be removed in        future releases, together with the option innodb_use_sys_malloc and with the InnoDB's internal memory allocator.
    170503 17:39:39 [Note] InnoDB: Using mutexes to ref count buffer pool pages
    170503 17:39:39 [Note] InnoDB: The InnoDB memory heap is disabled
    170503 17:39:39 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
    170503 17:39:39 [Note] InnoDB: Memory barrier is not used
    170503 17:39:39 [Note] InnoDB: Compressed tables use zlib 1.2.3
    170503 17:39:39 [Note] InnoDB: Not using CPU crc32 instructions
    170503 17:39:39 [Note] InnoDB: Initializing buffer pool, size = 16.0M
    170503 17:39:39 [Note] InnoDB: Completed initialization of buffer pool
    170503 17:39:39 [Note] InnoDB: Highest supported file format is Barracuda.
    170503 17:39:39 [Note] InnoDB: The log sequence numbers 0 and 0 in ibdata files do not match the log sequence number 1600674 in         the ib_logfiles!
    170503 17:39:39 [Note] InnoDB: Database was not shutdown normally!
    170503 17:39:39 [Note] InnoDB: Starting crash recovery.
    170503 17:39:39 [Note] InnoDB: Reading tablespace information from the .ibd files...
    170503 17:39:39 [Note] InnoDB: Restoring possible half-written data pages 
    170503 17:39:39 [Note] InnoDB: from the doublewrite buffer...
    170503 17:39:39 [Note] InnoDB: 128 rollback segment(s) are active.
    170503 17:39:39 [Note] InnoDB: Waiting for purge to start
    170503 17:39:40 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.22-72.0 started; log sequence number 1600674
    170503 17:39:40 [Note] Plugin 'FEEDBACK' is disabled.
    170503 17:39:40 [Note] Server socket created on IP: '::'.   

finally, I moved xampp/mysql/backup files into xampp/mysql/data and run mysql again.Then, it worked!But I don’t know why.What led to this problem.

Hope someone doubts for me！

Answer

If you’re not running XAMPP as an administrator, shutting down MySQL can cause corruption which means you have to repair or delete your tables. This can easily be avoided by running XAMPP as administrator.